Bone marrow access apparatus

ABSTRACT

A bone marrow access apparatus includes a bone penetrating member having an internal channel having an opening at a proximal end and an opening at a distal end, and a valve cap engaged with the bone penetrating member. The valve cap defines an interior cavity in which part of the bone penetrating member is situated to thereby secure the valve cap to the bone penetrating member. The valve cap includes a valve having an opening having an open state in which the channel is not obstructed and a closed state preventing flow of material through the channel. By being repeatedly switchable between the open and closed states, the valve controls access to the channel by bone marrow sampling and biopsy instruments.

FIELD OF THE INVENTION

The present invention relates generally to a bone marrow accessapparatus capable of providing easy, repeatable access to a patient'sbone marrow, tools for installing and removing the bone marrow accessapparatus, and instruments for use with the bone marrow access apparatuswhen installed.

BACKGROUND OF THE INVENTION

Bone marrow is the major site of blood cell formation and, while atbirth it is found within nearly all bones, by adolescence it is locatedprimarily within axial bones (e.g., pelvis and femur). The bone marrowexists in the inner portion of bones, referred to herein as the marrowspace, and contains the precursor stem cells that ultimately become redblood cells, white blood cells, and platelets.

Bone marrow aspirations and biopsies are common tests used to evaluatethe bone marrow for leukemias and other hematologic disorders, forexample. A sampling of the marrow from the marrow space can determinecell number, cell shape, and cell maturation. Special pathologic stainsand molecular studies on the marrow specimens can establish certaindiagnoses. Sampling of marrow from the marrow space may occur atmultiple times during a patient's treatment program to assess progress.

Conventionally, in order to access bone marrow of a patient, the bonemust be punctured each time a doctor needs to access the marrow. This ispainful for the patient, and imposes a significant burden on the doctorand healthcare resources. There exists a need for an implantable bonemarrow access apparatus that can be retained subcutaneously in the boneof a patient throughout the course of treatment to allow repeated accessto the bone marrow without requiring repeated bone punctures.

SUMMARY OF THE INVENTION

An object of one or more embodiments of the present invention is toprovide a bone marrow access apparatus that allows repeated sampling ofbone marrow at multiple timepoints without the need for repeated bonepunctures through the bone cortex (the outer portion of the bone thathas nerves which make punctures painful). The subcutaneous location ofthe apparatus, compared to an externalized device, is also likely toreduce infection from repeated sampling.

A bone marrow access apparatus in accordance with the invention includesa bone penetrating member having an internal channel having an openingat a proximal end and an opening at a distal end, and a valve capengaged with the bone penetrating member. The valve cap defines aninterior cavity in which part of the bone penetrating member is situatedto thereby secure the valve cap to the bone penetrating member. Thevalve cap includes a valve having an opening having an open state inwhich the channel is not obstructed and a closed state preventing flowof material through the channel. The valve is repeatedly switchablebetween the open and closed states. The valve controls or regulatesaccess to the channel by bone marrow sampling and biopsy instruments.

One advantage of the bone marrow access apparatus is that the valve capserves two important functions, namely, it includes a valve thatcontrols access to the channel and it also includes structure to enableit to be secured to the bone penetrating member. This structure may beone or more walls that define the interior cavity in which part of thebone penetrating member is situated. By combining the securing structurethat secures the valve cap and the bone penetrating member together withthe valve, an enhanced bone marrow access apparatus is provided.

Another advantage of the bone marrow access apparatus is that itprovides a cushioning effect by interposing a soft material between theusually hard bone penetrating member and the surface of the bone. Tothis end, the valve cap includes a peripheral wall situated outward ofpart of the bone penetrating member, and a lower rim coupled to a loweredge region of the peripheral wall and which is made of a soft orcushioning material. The lower rim extends inward from the peripheralwall to cause the lower rim to lie between part of the bone penetratingmember and a surface of the bone when the bone marrow access apparatusis engaged with the bone. The lower rim thus performs the cushioningeffect and also serves to secure the valve cap to the bone penetratingmember.

The valve cap may be provided at a proximal end portion of the bonepenetrating member, in which case, the valve is situated above the bonepenetrating member, e.g., in an upper wall extending from an upper edgeregion of the peripheral wall. At least this portion of the valve cap ispreferably made of a soft elastomer that is atraumatic, although theentire valve cap may be made of an atraumatic material. The softatraumatic covering is important to prevent erosion of the skin andtissues over the device. As an alternative position for the valve, itmay be invaginated (or recessed) into the channel of the bonepenetrating member, whether the valve cap is at the proximal end portionof the bone penetrating member or elsewhere.

A bone marrow access system or kit includes the bone marrow accessapparatus as described above in any of its configurations and one ormore instruments configured to pass through the opening at the proximalend of the channel into the channel and through the opening at thedistal end of the channel and thereby access the bone marrow space.These instruments may be straight sampling needles or sampling needleswith a curved tip that is able to be urged into a straight condition inorder to pass through the channel of the bone penetrating member andwill otherwise have its curved form. The curvature of the tip allows forgreater penetration into areas of the marrow space for sampling andbiopsy purposes.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be more fully understood from the followingdetailed description of embodiments thereof, taken together with thedrawings, in which:

FIG. 1 is a perspective view of a bone marrow access apparatus inaccordance with the invention;

FIG. 2 is a front view of the bone marrow access apparatus shown in FIG.1;

FIG. 3 is a cross-sectional view taken along the line 3-3 in FIG. 2;

FIG. 4 is a rear perspective view of the valve cap of the bone marrowaccess apparatus shown in FIG. 1;

FIG. 5 is a rear view of the valve cap shown in FIG. 4;

FIG. 6 is a cross-sectional view taken along the line 6-6 in FIG. 5;

FIG. 7 is a cross-sectional view showing the bone marrow accessapparatus installed in connection with a bone;

FIG. 8 is a view showing a preparatory stage for installation of thebone marrow access apparatus shown in FIG. 1;

FIG. 9 is a perspective view of a delivery tool used for installing thebone marrow access apparatus shown in FIG. 1;

FIG. 10 is a view showing an initial installation stage of the bonemarrow access apparatus shown in FIG. 1 with the delivery tool shown inFIG. 9;

FIG. 11 is a view showing the final installation stage of the bonemarrow access apparatus shown in FIG. 1 with the delivery tool shown inFIG. 9;

FIG. 12 is a perspective view of a straight sampling needle used withthe bone marrow access apparatus shown in FIG. 1;

FIG. 13 is a cross-sectional view of the sampling needle shown in FIG.12 shown during use;

FIG. 14 is a perspective view of a sampling needle with a curved tipused with the bone marrow access apparatus shown in FIG. 1;

FIG. 15 is a cross-sectional view of the sampling needle with a curvedtip shown in FIG. 14 shown during use;

FIG. 16 is a perspective view of a removal tool used to remove the bonemarrow access apparatus shown in FIG. 1 from its installation in a bone;and

FIG. 17 is a view showing the manner in which the bone marrow accessapparatus shown in FIG. 1 can be removed using a removal tool.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the accompanying drawings wherein like reference numbersrefer to the same or similar elements, FIGS. 1-3 show a bone marrowaccess apparatus 10 in accordance with the invention. Bone marrow accessapparatus 10 includes a bone penetrating member 12 configured topenetrate into a bone across the bone cortex to enable access to amarrow space in the bone during use of the bone marrow access apparatus10, and a valve cap 14 configured to control access to the marrow spacethrough the bone penetrating member 12 and partly cover the bonepenetrating member 12. The bone penetrating member 12 and valve cap 14are formed as separate components and are engaged with one another in asecure manner for use of the bone marrow access apparatus 10.

Bone penetrating member 12 includes an axially extending, substantiallytubular insertion portion 16 having a spiral thread 18 on an outersurface 20 (see FIG. 2). The spiral thread 18 enables the bonepenetrating member 12 to be urged into the bone cortex upon rotation ofthe bone penetrating member 12 via a tool described below. An exteriorsurface of the insertion portion 16 can be provided with fluted edges 22at the bottom thereof to help cut into the bone cortex duringinstallation of the bone marrow access apparatus 10.

Spiral thread 18 aids in placement of the insertion portion 16 in thebone cortex, e.g., it enables the insertion portion 16 to be tapped orscrewed into the bone cortex, and provides for secure retention of theinsertion portion 16 in the bone cortex, and thus the bone marrowapparatus 10 in its use position in connection with the bone. Instead ofa spiral thread 18, alternative structure may be provided on the outersurface 20 of the insertion portion 16 that functions to enableinsertion of the bone penetrating member 12 into the bone cortex andretention therein. Such alternative structure is known to those skilledin the art to which this invention pertains, and all such structure thatenables the insertion portion 16 to engage with and be retained in abone is referred to as insertion and retention means herein. Detailsabout the manner in which bone marrow access apparatus 10 is installedand used are described below.

Bone penetrating member 12 also includes a head portion 24 having alarger cross-sectional shape than that of the insertion portion 16. Thehead portion 24 has a bottom surface 26 adjacent the insertion portion16 and a step 28 peripherally outward of the bottom surface 26. The step28 provides an outer peripheral surface of the head portion 24 with aperipheral indentation which engages with part of the valve cap 14 toprovide for secure engagement of the valve cap 14 to the bonepenetrating member 12 as discussed below. The head portion 24 may have ahexagonal cross-section or a circular cross-section in a planeperpendicular to the axial direction of the bone penetrating member 12,or may have other cross-sectional shapes such as square, triangle, Torx,and the like.

An internal channel 30 extends through the bone penetrating member 12between an opening 32 at a proximal end 34 in the upper surface of thehead portion 24, and an opening 36 at a distal end 38 at the bottom ofthe insertion portion 16. Through channel 30, bone marrow can be removedfrom the marrow space in the bone when the bone marrow access apparatus10 is engaged with the bone. Removal of bone marrow from the marrowspace is commonly referred to as bone marrow sampling.

To this end, the axial length of the insertion portion 16 of the bonepenetrating member 12 is dimensioned to at least reach the marrow spaceof a particular bone when the head portion 24 is on the surface of thebone (see FIG. 11). Thus, there may be a plurality of different lengthsof insertion portions 16 of bone penetrating members 12, and a suitablelength is selected based on the bone on which the bone penetratingmember 12 is being installed and possibly also the size of the patient.

Part of the internal channel 30 is formed as a seat 40 below the uppersurface of the head portion 24 (see FIG. 3). Seat 40 is designed tocooperate with various tools to enable the bone penetrating member 12 tobe screwed into the bone and to facilitate removal of the bone marrowaccess apparatus 10 therefrom (discussed below). Seat 40 may have aparticular shape or construction to enable rotation of the tools toimpart rotation of the bone penetrating member 12 when the tools aremated with the seat 40 of the bone penetrating member 12. For example, apolygonal, e.g., hexagonal shape, for the seat 40 with a correspondinghexagonal shape for a flange of the tools is possible.

Another part of the channel 30 is formed as a valve relief space 42 (seeFIG. 3). Valve relief space 42 is designed to accommodate leaflets of avalve 52 that are pushed inward into the channel 30 during installationand use of the bone marrow access apparatus 10 (see FIGS. 8-10).

Internal channel 30 has a particular size to enable bone marrow samplingwhen the bone marrow access apparatus 10 is in use. The channel 30 mayhave a diameter in a range from about 2.0 mm to about 4.2 mm (8-15 G) toallow for insertion of large-sized needles and other types of standardlyused sampling instruments. The dimensions of the channel 30, i.e., itslength and diameter, are also selected to enable tilting of a samplingneedle to allow it to reach fresh areas of the marrow space afterrepeated sampling. The degree of tilting of the needle is thus dependenton the diameter of the needle and the diameter of the channel 30. In oneembodiment, the channel 30 is dimensioned to enable a needle having asize of 13 G to tilt while in the channel by about 15 degrees in alldirections relative to a central axis of the channel 30, therebyproviding a total degree of tilt of about 30 degrees. In anotherembodiment, the channel 30 is dimensioned to enable a needle having asize of 15 G to tilt by about 10 degrees to each side, thereby providinga total degree of tilt of about 20 degrees. The 15 G needle may be usedto sample cells via needle aspiration, while the 13 G instrumentretrieves worm-like tissue samples and benefits more from tilting tosource a fresh sampling area. Of course, different combinations ofdifferently sized needles and channels 30 provide different tilt angles.A medical practitioner using bone marrow access apparatus 10 may beapprised of the needle sizes that can be used with each size of bonemarrow access apparatus 10 and the obtainable tilt angles.

In a preferred embodiment, the bone penetrating member 12 is made of arigid biocompatible material. Suitable materials include, withoutlimitation, stainless steel, titanium, nitinol, and polyetheretherketone(PEEK).

Various constructions of the bone penetrating member 12 and valve cap 14are envisioned to provide for secure retention of the valve cap 14 inconnection with the bone penetrating member 12 for installation and useof the bone marrow access apparatus 10. One such construction is toprovide the valve cap 14 with one or more walls that define an interiorcavity 44 dimensioned to accommodate at least part of the bonepenetrating member 12.

In the illustrated embodiment, the valve cap 14 includes a peripheralwall 46 arranged outward of the head portion 24 of the bone penetratingmember 12 (see FIGS. 4 and 6) The peripheral wall 46 may entirelysurround the head portion 24 of the bone penetrating member 12 withwhich the valve cap 14 is operatively engaged. The peripheral wall 46has an inner surface having generally the same cross-sectional shape (ina plane perpendicular to the axis of the bone marrow access apparatus10) as the outer surface of the head portion 24 of the bone penetratingmember 12, and which is only slightly larger to provide for a tight fitbetween the valve cap 14 and the bone penetrating member 12.

Valve cap 14 also includes an upper wall 48 extending inward from anupper edge region of the peripheral wall 46 and a lower rim 50 extendinginward from a lower edge region of the peripheral wall 46 (see FIG. 6).When the valve cap 14 is engaged with the bone penetrating member 12,the upper wall 48 is situated above the upper surface of the headportion 24 of the bone penetrating member 12 and the lower rim 50 is inthe step 28 and thus underlies a peripheral edge region of the headportion 24 of the bone penetrating member 12 (see FIG. 3). With theupper wall 48 above the head portion 24 and the lower rim 50 in the step28 below the head portion 24, the valve cap 14 is secured to the bonepenetrating member 12.

Instead of upper wall 48 and lower rim 50, another structure forsecuring the valve cap 14 to the bone penetrating member 12, whether thehead portion 24 or another part of the bone penetrating member 12, maybe used in the invention. Such alternative securing structure whichperforms the same function as the upper wall 48 and lower rim 50 in thesame or a similar manner is readily ascertainable by those skilled inthe art to which this invention pertains and is considered to be withinthe scope of the invention. All such structure is considered to beencompassed within the phrase securing means for securing the valve capto the bone penetrating member.

An important characteristic of the valve cap 14 is that at least theportion above the head portion 14 of the bone penetrating member 12 ismade of atraumatic material, i.e., part or all of the upper wall 48.Soft elastomers known to be atraumatic may preferably be used. Use ofatraumatic material prevents damage to the skin above the bone marrowaccess apparatus 10 when present in a human body. It is possible to formthe valve cap 14 entirely from atraumatic material. Exemplifyingcharacteristics of an atraumatic material include it being soft andhaving low durometer, with the purpose being to prevent skin erosion anddegradation, and provide a cushion layer between the skin and the bonepenetrating member.

The upper wall 48 includes a valve 52 situated entirely above the bonepenetrating member 12 and that has an opening 54 that controls access tothe channel 30 (see FIGS. 1 and 6). It is envisioned that the valve 52may be situated in a part of the valve cap 14 other than in the upperwall 48. For example, the valve 52 may be invaginated (or recessed) intothe channel 30 of the bone penetrating member 12.

Valve opening 54 has an open state in which the channel 30 is notobstructed and a default closed state in which it is closed and materialflow between the openings 32, 36 of the channel 30 is prevented. In oneembodiment, the valve cap 14 includes only a single valve.

Valve 52 has a particular construction to enable the valve opening 54 tobe repeatedly switchable between the open and closed states. Forexample, the valve 52 may be a single slit valve as shown in FIG. 1, oralternatively, an intersecting slit valve. Such valves have leaflets 56that contact one another in a default closed state and must be urgedapart from one another to form the opening 54. When urged apart from oneanother, for example, by a sampling needle being introduced through thechannel 30 into the marrow space in the bone, the leaflets 56 areaccommodated in the valve relief space 42. Valve 52 may also be aduck-bill valve. Generally, the valve 52 is designed for repeatedopening and closing of the opening 54, without losing integrity orreleasing fragments thereof.

Valve 52 is representative of an access control component that controlsaccess to the channel 30 and other access control components thatperform the same functions for the valve 52 described herein may be usedas alternative to the valve 52. Such alternative access controlstructure that performs the same function as the valve 52 in the same ora similar manner is readily ascertainable by those skilled in the art towhich this invention pertains and is considered to be within the scopeof the invention. A valve and all such comparable access controlcomponents are considered to constitute access control means forcontrolling access to the channel 30.

In one embodiment, the valve cap 14 has a unitary construction. Thismeans that it is formed as a single unit or single piece. It can beentirely made of substantially the same soft elastomer, preferably onethat has a durometer of 5-50 Shore A. For example, the valve cap 14 maybe made of silicone or polyurethane.

Bone marrow access apparatus 10 is installed in connection with a bone 8since only part of the bone marrow access apparatus 10 is situated inthe bone 8 (for example, the insertion portion 16 of the bonepenetrating member 12 as shown in FIG. 7) while another part is situatedon, above and/or outside of the bone 8 (for example, the head portion 24of the bone penetrating member 12 and the valve cap 14 as shown in FIG.7).

A typical, but non-limiting, installation of the bone marrow accessapparatus 10 in connection with a bone entails first connecting the bonepenetrating member 12 and the valve cap 14. This is achieved byinserting the head portion 24 of the bone penetrating member 12 throughan opening defined by the lower rim 50 into the interior cavity 44 untilthe lower rim 50 has been urged into the step 28 in the head portion 24of the bone penetrating member 12. The head portion 24 should fit snuglyinto the interior cavity 44 defined by the valve cap 14.

For insertion of the insertion portion 16 of the bone penetrating member12 into the bone 8, a delivery tool 70 is specially designed for thispurpose, shown in FIGS. 8 and 9. Delivery tool 70 includes a handle 72,and a rigid, elongate shaft 74 attached at one end region to the handle72 and attached at an opposite end region to a flange 76. A drill bit 78is attached to the shaft 74 below the flange 76, or may be attached tothe flange 76. Flange 76 is shaped to fit in the seat 40 in the headportion 24 of the bone penetrating member 12 (see FIGS. 10 and 11).

Dimensions of the delivery tool 70 are specific to the particular bonepenetrating member 12 being installed, so that a plurality of deliverytools 70 may be required for differently dimensioned bone penetratingmembers 12. More particularly, the length of the drill bit 78 should begreater than the length of the channel 30 in the insertion portion 16 sothat, when the flange 76 is situated in the seat 40, the drill bit 78will extend below a bottom surface of the insertion portion 16 of thebone penetrating member 12 (see FIG. 11). This is necessary because thedrill bit 78 often creates or completes drilling of a bone channelthrough the bone cortex to the marrow space 2, which bone channel startswith a pilot hole 4. Obviously, the diameter of the drill bit 78 must besmaller than the diameter of the channel 30 to enable the drill bit 78to enter into and pass through the channel 30 (see FIGS. 10 and 11).

In an exemplifying installation method using the tool 70, the handle 72of the delivery tool 70 is grasped and the drill bit 78 is aligned withthe opening in the valve 52 leading to the channel 30 while the bonemarrow access apparatus 10 has not yet been inserted into the bone 8(FIG. 8). The drill bit 78 is then inserted through the opening 54 inthe valve 52 into the channel 30 until the flange 76 rests on the seat40 (FIG. 10).

The tool 70, with the attached bone marrow access apparatus 10, isinserted through an incision in the patient's skin to insert theinsertion portion 26 of the bone penetrating member 12 into the pilothole 4. The bone marrow access apparatus 10 is thus inserted into thepilot hole 4 in the bone 8 extending from the outer surface 6 of thebone 8 toward the marrow space 2, which pilot hole 4 may be onlyinitially formed by the drill bit 78 (see FIG. 10). This insertion isaided by the thread 18 on the outer surface 20 of the insertion portion16 of the bone penetrating member 12 which grips the surface of the bonecortex defining the pilot hole 4. In one embodiment, the pilot hole 4may be formed by puncturing the bone 8 using a bone puncture needle. Forexample, the pilot hole 4 may be created through the cortical layer.Alternatively, the self-tapping delivery tool 70 can create the pilothole 4 as it delivers the bone marrow access apparatus 10.

The tool 70 is then rotated, while maintaining the flange 76 in the seat40, to cause the bone penetrating member 12 to be further inserted intothe bone 8. Rotation of the tool 70 continues until the drill bit 78completes a channel through the bone cortex into the marrow space 2 andthe lower surface of the lower rim 50 of the valve cap 14 rests on thesurface 6 of the bone 8 (FIG. 11).

By interposing the lower rim 50 between the head portion 24 of the bonepenetrating member 12 and the surface 6 of the bone 8, a cushioningeffect is provided by the lower rim 50. The lower rim 50 is preferablymade of a soft elastomer which can be compressed and thereby cushionsimpact of the head portion 24 of the bone penetrating member 12 againstthe bone surface 6.

After the bone marrow access apparatus 10 attains the position shown inFIG. 11, the tool 70 is removed from engagement with the bone marrowaccess apparatus 10 by lifting it upward. The tool 70 is then removedthrough the opening 54 defined by the valve 52 causing the opening 54 inthe valve 52 to close. The tissues above the apparatus are thensurgically closed. The final installed position of the bone marrowaccess apparatus 10 is shown in FIG. 7. Note that glue or anotheradhesive is not required to install the bone marrow access apparatus 10.

Once the bone marrow access apparatus 10 is installed in connection witha bone 8, it can be used for sampling bone marrow whenever such samplingis desired either for biopsy or aspiration dependent on which instrumentis used. Each time bone marrow is sampled, the surgeon would press theskin in the known area of the bone marrow access apparatus 10 to locatethe bone marrow access apparatus 10. Once located, the surgeon wouldpress the skin over the valve cap 14, and insert an instrument such as asampling needle through the skin and through the opening 54 of the valve52 into the channel 30 and out of the distal opening 36 of the channel30 into the marrow space 2. A sampling needle, or other type ofinstrument, having a size (gauge) that fits in the channel 30 isobviously selected. The penetration depth of the sampling needle orother instrument into the marrow space 2 is also variable by thesurgeon.

If a straight sampling needle 66 is selected, the sampling needle 66 maybe tilted to sample a fresh area of the marrow space 2 for bone marrow(see FIGS. 12 and 13).

As an alternative, a curved sampling needle 80 may be used (FIG. 14).The curved sampling needle 80 includes an inner tube 82 with a curve ata distal end and a straight outer tube 84. The curved inner tube 82allows for sampling bone marrow from a larger region of the marrow space2 since it can be inserted to different depths and rotated to reachdifferent directions (see FIG. 15). To aid in curving of the inner tube82, it is optionally provided with cut-outs 98 at the distal end region.These cutouts 98 may be formed by a laser.

Curved sampling needle 80 may be made of nitinol and the curved innertube 82 sharpened to facilitate for penetration of the marrow. Thecurved inner tube 82 assumes a straight condition as it passes throughthe channel 30 since it is retained in the straight outer tube 84, butthen curves to its initial condition after passing through the opening36 and then out of the outer tube 84 (FIG. 14). The inner tube 82 ismade of a material that is sufficiently rigid to push through the outertube 84 in order to collect a tissue sample, yet configured to revert toa curved state at the distal end to increase the sampling area, and suchmaterials are readily known or ascertainable to those skilled in the artto which this invention pertains in view of the disclosure herein.Instead of a straight outer tube 84, a straight internal stylet may beprovided to allow for entry of the curved inner tube 82 into and passagethrough the channel 30, and then unsheathing of the inner tube 82 toenable it to return to its natural curve when reaching the marrow spacefor sampling.

In one embodiment, the needles 66, 80 have a stylet that allows theneedles 66, 80 to penetrate the skin and get to the location in themarrow space of the bone. The stylet is removed allowing the hollowchannel to now be able to aspirate the marrow or biopsy it. Withoutusing the stylet, the needles 66, 80 would core the skin and muscles asthey are pushed in. It is also possible to use a guide needle thatwould, with a stylet, be pushed into the marrow space and then when thestylet is removed, different needles could be inserted through thechannel to sample marrow without having to penetrate the skin fresh witheach needle.

Regardless of which type of sampling needle is used, after the samplingis completed, the needle is removed from the channel 30 and withdrawnthrough the valve 52 and skin. The valve 52 closes its opening 54thereby preventing material flow out of and into the marrow space 2.

The sampling needles 66, 80 preferably include depth of insertionindicators so that the surgeon can read the indicators and determine thesampling depth. This allows the surgeon to sample different depths inthe bone marrow space 2 at different times, for example, to sample atweek 1 at X depth and week 2 at a different Y depth.

Once the bone marrow access apparatus 10 is no longer needed for bonemarrow sampling, it can be removed. Removal generally involves rotatingthe bone marrow access apparatus 10 out of the hole in the bone 8. Ifprovided with a spiral thread 18, this may be attained by grasping thevalve cap 14, applying pressure against the head portion 24 of the bonepenetrating member 12 and then rotating it in the opposite directionthan the direction in which bone penetrating member 12 was inserted intothe hole in the bone 8.

A removal tool 86 is specially designed to ease removal of the bonemarrow access apparatus 10 (FIG. 16). Removal tool 86 includes a handle88, and a shaft 90 attached at one end region to the handle 88 andattached at an opposite end region to a flange 92. Flange 92 is shapedto fit in the seat 40 in the head portion 24 of the bone penetratingmember 12.

For removal of the bone marrow access apparatus 10, the surgeon insertsthe removal tool 86 through an opening in the skin over the bone marrowaccess apparatus 10 and then inserts the removal tool 86 through theopening 54 in the valve 52 into the channel 30 until the flange 92 restson the seat 40 (FIG. 17). The tool 86 is then rotated, while maintainingthe flange 92 in the seat 40, to cause the bone penetrating member 12 towithdraw from the bone hole. Rotation of the tool 86 continues until theinsertion portion 16 of the bone penetrating member 12 is completelyfree of the bone and then the tool 86 and bone marrow access apparatus10 engaged therewith is withdrawn through the skin of the patient. Thevalve cap 14 holds the bone penetrating member 12 on the removal tool 86as it is lifted up. The leaflets 56 will be on the top of the flange ofthe removal tool 86 with some counterforce.

Delivery and removal tools 70, 86 may be single use tools or designedfor multiple uses.

Variations of the embodiments described above and illustrated in thedrawings are considered to be within the scope of the invention, andthus the scope of the invention should be determined by the appendedclaims and their legal equivalents, rather than by the examples given.In addition, apparatus and methods disclosed in U.S. provisional patentapplication Ser. No. 62/062,105 filed Oct. 9, 2014, U.S. provisionalpatent application Ser. No. 62/404,551 filed Oct. 5, 2016 and U.S.nonprovisional patent application Ser. No. 15/024,522 filed Mar. 24,2016 may be incorporated into and/or used with the inventions disclosedabove and all of these applications are incorporated by referenceherein.

The invention claimed is:
 1. A bone marrow access apparatussubcutaneously implantable in a bone of a patient to enable biopsy ofbone marrow, said bone marrow access apparatus comprising: a bonepenetrating member having threads on an outer surface thereof and aninternal channel having an opening at a proximal end and an opening at adistal end, said threads having a hardness and sharpness such that saidbone penetrating member is screwable into the bone to access the bonemarrow; and a valve cap engaged with said bone penetrating member, saidvalve cap defining an interior cavity in which at least part of saidbone penetrating member is situated, said valve cap comprising a valvehaving an opening having an open state in which said channel is notobstructed and a closed state preventing flow of material through saidchannel, said valve being repeatedly switchable between the open andclosed states, and said channel being sized to receive an instrument forobtaining a biopsy of the bone marrow, wherein said bone penetratingmember comprises an axially extending insertion portion and a headportion having a larger cross-sectional area than said insertionportion, said head portion having a bottom surface adjacent saidinsertion portion and a step peripherally outward of said bottom surfaceand providing an outer peripheral surface of said head portion with anindentation, said valve cap further comprises a peripheral wall to whichsaid valve is coupled, and a lower rim coupled to a lower edge region ofsaid peripheral wall, said interior cavity being defined by said valve,said peripheral wall and said lower rim, said lower rim extending inwardfrom said peripheral wall into said indentation to thereby secure saidvalve cap to said bone penetrating member.
 2. The apparatus of claim 1,wherein said valve cap and said bone penetrating member are separablefrom one another.
 3. The apparatus of claim 1, wherein said valve caphas a unitary construction.
 4. The apparatus of claim 1, wherein saidvalve cap is provided at a proximal end portion of said bone penetratingmember and said valve is situated above said bone penetrating member. 5.The apparatus of claim 1, wherein said valve cap is provided at aproximal end portion of said bone penetrating member and said valve isinvaginated into said channel of said bone penetrating member.
 6. Theapparatus of claim 1, wherein at least a portion of said valve cap abovean upper surface of said bone penetrating member is made of a softelastomer that is atraumatic.
 7. The apparatus of claim 1, wherein saidvalve cap is entirely made of substantially the same soft elastomerwhich has a durometer of 5-50 Shore A.
 8. The apparatus of claim 1,wherein said peripheral wall has an upper edge region to which saidvalve is coupled such that said valve is situated above an upper surfaceof said bone penetrating member, and said peripheral wall is situatedoutward of said at least part of said bone penetrating member.
 9. Theapparatus of claim 1, wherein said lower rim extending underlies part ofsaid bone penetrating member, and said peripheral wall is situatedoutward of said at least part of said bone penetrating member.
 10. Theapparatus of claim 1, wherein said peripheral wall has an upper edgeregion to which said valve is coupled, and said peripheral wall issituated outward of said at least part of said bone penetrating member.11. The apparatus of claim 1, wherein said valve comprises a pluralityof leaflets that define at least one slit that constitutes said openingof said valve of said valve cap, said leaflets being movable into saidchannel when said opening is in its open state.
 12. The apparatus ofclaim 1, wherein said valve is the only valve in said valve cap.
 13. Theapparatus of claim 1, wherein said channel has a diameter in a rangefrom about 2.0 mm to about 4.2 mm.
 14. The apparatus of claim 1, whereinsaid channel extends through said insertion portion and said headportion between said openings at the proximal and distal ends.
 15. Theapparatus of claim 1, wherein said bone penetrating member has an uppersurface and a seat below said upper surface configured to engage with aninstallation and removal instrument.
 16. A bone marrow access system,comprising: a bone marrow access apparatus subcutaneously implantable ina bone of a patient to enable biopsy of bone marrow, said bone marrowaccess apparatus comprising: a bone penetrating member having aninternal channel having an opening at a proximal end and an opening at adistal end adapted to open into a bone marrow space in the bone toenable access to the bone marrow; and a valve cap engaged with said bonepenetrating member, said valve cap defining an interior cavity in whichat least part of said bone penetrating member is situated, said valvecap comprising a valve having an opening having an open state in whichsaid channel is not obstructed and a closed state preventing flow ofmaterial through said channel and being repeatedly switchable betweenthe open and closed states; and an instrument for obtaining a biopsy ofthe bone marrow, said instrument being configured to pass through saidopening at the proximal end of said channel of said bone marrow accessapparatus into said channel and through said opening at the distal endof said channel and thereby enable said instrument to obtain the biopsyof the bone marrow in a state in which said instrument accesses the bonemarrow space, wherein said valve cap further comprises a peripheral walland a lower rim coupled to a lower edge region of said peripheral wall,said lower rim extending inward from said peripheral wall to cause saidlower rim to lie between part of said bone penetrating member and asurface of the bone when said bone marrow access apparatus is engagedwith the bone and thereby cushion said bone penetrating member on thebone and also secure said valve cap to said bone penetrating member,said peripheral wall being situated outward of said at least part ofsaid bone penetrating member.
 17. The system of claim 16, wherein saidbone penetrating member comprises an axially extending insertion portionthat extends through the cortex of the bone when said bone marrow accessapparatus is engaged with the bone and a head portion having a largercross-sectional area than said insertion portion and that lies exteriorof the bone when said bone marrow access apparatus is engaged with thebone, said channel extending through said insertion portion and saidhead portion between said openings at the proximal and distal ends.